A machine that is used for both a miter cut operation and a bench cut operation is known as a compound saw. Among the compound saws, there is a type of compound saw which has a frame and a deck plate fixed together, and implement a switch between a miter cut operation mode and a bench cut operation mode by a relative raising-lowering motion of a saw blade relative to the frame and the deck plate. When a part of the saw blade passes through a saw blade slot on the deck plate and so as to be higher than the upper plane of the deck plate, the bench cut operation can then be performed. Usually, when the miter cut operation is to be performed, the whole of the saw blade is hidden under the upper plane of the deck plate so that the cut operation is performed by using a lower-half portion of the saw blade.
In the related art, there are many kinds of elevating mechanisms and protective structures for saw blades. There is a representative elevating mechanism and a protective structure for saw blade disclosed in ZL201410203008.8, which use a screw pushrod mechanism, a worm and gear mechanism, a bevel gear mechanism, etc., to achieve a purpose of raising and lowering the saw blade, while equipping with related connecting rod system and shielding case to achieve a linkage protection for the saw blade.
Although these mechanisms and systems could work, their structures are complex, thus adversely affecting economy, simplicity of use and maintenance and reliability of the compound saw.